Pressure-applying device

ABSTRACT

This device disclosed includes an airtight container of flexible material having a valved conduit communicating therewith. Another conduit is connected to the valve and to a source of vacuum. The valve has an inlet from ambient atmosphere. Independent control means are included in the valve for selectively interconnecting the conduits and the inlet.

United States Patent [72] Inventor CarrolC.Sachs [56] References Cited9938 Cybourn Ave., Sunland, Calif. 91040 UNITED STATES PATENTS [21] P1,595,487 8/1926 Minton 156/381 [22] Flled Mar. 10,1969 2 3 M 156 580 45Patented on. 26 1971 983,553 1 4 3,405,019 10/1968 Selletal. 156/382Primary Examiner- Leland A. Sebastian AtlrneyRoger A. Marrs [54] si fs gs P g DEvIcE ABSTRACT: This device disclosed includes an airtightconalms rawmg tainer of flexible material having a valved conduit commu-[52] US. Cl 156/382, nicating therewith. Another conduit is connected tothe valve 156/287 and to a source of vacuum. The valve has an inlet fromam- [51] Int. Cl B32b 31/20 bient atmosphere. Independent control meansare included in [50] Field of Search 156/293, the valve for selectivelyinterconnecting the conduits and the 287,382,499,580,583 inlet.

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PRESSURE-APPLYING DEVICE One use for which the valve of this inventionis especially adapted is in vacuum systems employed for pressure-forminglaminated plastic parts. To produce such parts, a bag forming and skinpacking process may be followed. By that method, layers ofresin-impregnated glass cloth or the like are layed up on a die having aconfiguration conforming to that desired for a completed part. The dieand laminations then are inserted into an airtight flexible container,generally a bag of polyvinyl alcohol material, which is sealed andevacuated in order to apply atmospheric pressure to the part. In someinstances the bag is located in an autoclave for achieving greaterpressures, and normally it is subjected to heat for curing the resin ofthe part. The sealant for the open end of the bag is usually zincchromate which is applied along mating marginal surfaces of the end ofthe bag.

A length of tubing is inserted between a portion of the mating marginalsurfaces into the bag and connected to a source of vacuum for drawingair from within the bag. A simple plug valve has been included in thevacuum line to either connect or disconnect the interior of the bag andthe source of vacuum. When the bag initially is subjected to a vacuum,the sheet material of the bag invariably forms wrinkles, includingwrinkles where the bag contacts the laminations to be cured. Suchwrinkles are unacceptable, at least in many areas of a typical part,because the wrinkles mark the part as the pressure is applied and thecure is effected resulting in a lamination not strictly corresponding tothe die. This necessitates the additional step of removing wrinkles inthe bag material from critical areas of the part before the part iscured.

In the past, it has been customary to break the sea] at the end of thebag by separating the marginal edges so that the vacuum is released andthe wrinkles may be worked away from the part. A partial vacuum isnecessary as the bag is straightened, however, so that the wrinkles canbe effectively moved yet no new wrinkles will take their places.Therefore, the valve in the vacuum line is left open and the seal isbroken at only a limited portion ofthe end of the bag. This enables thevacuum pump to maintain the pressure within the bag at a value belowatmospheric. After the wrinkles have been removed, the open end of thebag again is sealed, full vacuum is pulled and the remainder of theforming process may take place.

This procedure obviously is disadvantageous because of the time involvedin first separating the marginal portions of the bag to break the sealand then resealing after the wrinkles have been removed. Care must beexerted to provide only a limited aperture into the bag when the openingis made so that a partial vacuum can be maintained by continuedoperation of the vacuum pump. In addition, the open connection betweenthe atmosphere and the vacuum line permits contamination of the vacuumsource as air continuously is drawn into the bag and then out throughthe vacuum line. Also, of course, the vacuum source must perform thework of pumping air all during the time the wrinkles are being removedfrom the bag.

One of the most troublesome conditions with conventional bag forming isencountered after the assembly has been heated. Frequently, the valvesin the vacuum line stick after being subject to heat, becoming verydifficult to operate and requiring early replacement. Only a simple "on"or "off" type control is possible with the valves customarily employed.

According to the provisions of this invention, a valve may be includedin the vacuum line which provides a close control of the amount ofvacuum in the bag, is quick and easy to operate, and is not adverselyeffected by elevated temperatures. One embodiment of this valve includesa body having three ports, one of which may be connected to either ofthe other two as controlled by two spring pressed poppets. A resilientseal of silicone rubber is included in each poppet, and cam leveractuators operate each poppet independently. This valve is used in bagforming to maintain the proper pressure within the bag at all times.

Aside from providing an excellent closure seal, the valve is not subjectto stoppage or faulty operation which normally occurs when conventionalvalves are employed, since the valve of the present invention is notsusceptible to contamination. Because of this feature, the valve may bereadily employed in fluid dispensing applications such as soda or watervalves in the food industry where sanitation is of paramount importanceor for certain types of exotic fluid control in the atomic energyprocesses and systems. In instances requiring precisely metered mixingof different fluids, the present valve has been of particular advantagesuch that the spring biased poppets are independently controlled by thecam lever actuators that may be manually operated or may be incorporatedinto an automatic powered or electromechanical operating system. Such asystem is susceptible to be programmed to effect the desired meteredmixing of the fluids.

Therefore, it is a primary object of the present invention to provide anovel valve apparatus operable to precisely control metered fluidsthroughout a process cycle that is resistant to high temperatures.

Another object of the present invention is to provide a novel fluidcontrol valve having improved control characteristics includingeffective closure and freedom from contamination.

An additional object of the present invention is to provide an improvedarrangement for vacuum bag forming whereby the vacuum created may beprecisely bled from the interior of the bag by a manually operatedactuator.

Yet another object of the present invention is to provide a novel valvewhich gives ease of operation and durability of service, particularly influid control and dispensing applications requiring sanitary handling ofthe fluid.

A further object of this invention is to provide an improved arrangementfor controllably removing wrinkles in a bag forming operation withoutnecessitating the separation of the edge marginal regions of adjacentbag sides.

Yet another object of this invention is to provide means for selectivelycontrolling the pressure within a sealed container as employed inapplications requiring pressure to be applied to a part.

The features of the present invention which are believed to be novel areset forth with particularity in the appended claims. The presentinvention, both as to its organization and manner of operation, togetherwith further objects and advantages thereof, may best be understood byreference to the following description, taken in connection with theaccompanying drawings, in which:

FIG. 1 is a sectional view of the fluid control valve of the presentinvention;

FIG. 2 is a sectional view of the valve shown in FIG. I as in thedirection of arrows 2-2 thereof, illustrating the end of the poppet andits sealing seat;

FIG. 3 is a fragmentary side elevational view of the valve arrangementof FIG. 1 showing the bifurcated end portion of the cam lever actuatoremployed for one of the poppets;

FIG. 4 is a perspective view of the valve apparatus of FIG. 1 employedin conjunction with a bag forming arrangement when a vacuum is drawninitially within the bag;

FIG. 5 is a perspective view, similar to FIG. 4, but with the wrinklesin the bag material removed;

FIG. 6 is a schematic view illustrating the valve of FIG. I in positionfor drawing air from within the bag to remove material wrinkles; and

FIG. 7 is a schematic view, similar to FIG. 6, but with the valve closedto seal off the interior of the bag.

Referring to FIGS. 1, 2 and 3, a fluid control valve in accordance withthe present invention is indicated in the general direction of arrow 11that preferably is of stainless steel material and is provided withintercommunicating ports 12. 13 and I4, the former two of which arethreaded in the embodiment shown. Passageways I5 and 16 providecommunication through the valve body interconnecting the ports. Poppetassemblies l8 and 19 are inserted in the ends of the body and carryreciprocative poppets or plungers 20 and ZI, respectively, forcontrolling the flow of fluid through passageways l5 and 16. The shanksof poppets 20 and 21 are received within threaded members 22 and 23,conveniently formed with hexagonal heads located outside of the valvebody at its extreme opposite ends while the threaded portions 26 and 27of these members are held within complementary threaded end openings invalve body 1 1. Seal 29, preferably of heat resistant material such assilicone rubber and in the form of O-rings, prevent leakage around theexterior of the poppet assemblies. The ends of the body are recessed forreceiving these O-rings which will seal effectively even when thethreaded members 22 and 23 are only fingertight within the openings inthe ends of the body. This feature greatly enhances and facilitatesready maintenance and repair.

Poppet shanks 31 and 32 extend out through the hexagonal heads ofmembers 22 and 23 and are sealed to prevent leakage by O-rings 33 and 34adjacent shoulders 35 and 36 formed in the threaded members. Preferablyagain, a high temperature resistant material such as silicone rubber isutilized for the seal. Poppet closure heads 37 and 38 of the poppetassemblies are engaged by expansion springs 39 and 40, the other ends ofwhich bear against washers a1 and 42. A spring force, therefore,forcibly urges the heads of the poppets against annular tapered valveseats 43 and 44 to close passageways l and 16. The spring force reactingthrough washers 41 and 42 also urges the O-rings 33 and 34 againstshanks 31 and 32 of the poppets and the bores of members 22 and 23 toassure that a seal will be maintained. The poppet closure heads areprovided with coaxial recesses 45 and 36 having annular convergingtapered sidewalls 47 and 48 defining the recesses. At the base of thesidewalls terminating at the bottom of the recesses, elastomeric wait;50 and 51 are provided and which are disposed within retainer groovesformed in the closure heads so that the seals are held therein by meansof an interference type fit. The poppet heads tapered sidewalls matewith the tapered seats 43 and 44 so that the terminating ends thereofengage with seals 50 and 51 in an airtight manner when the poppets areurged thereagainst by the springs. Silicone rubber is used for thecomposition of these seals just as for the O-rings previously mentioned.

Actuation of the poppets is effected by cam levers 52 and 53 which arepivoted on pins 54 and 55 to the outer ends of the poppet shanks. Theseactuating members include bifurcated cam ends 56 and 57 which arerounded on one edge and adapted to engage the ends of hexagonal headmembers 22 and 23. The lengths of these cam ends beyond their pivotpoints 54 and 55 are such that when they are moved to a position ofalignment of the poppet shafts, they react against heads 22 and 23 tomove the poppets axially. By this construction, if a lever 53 ispivoted, for example, cam end 57 reacts against head 23 thereby axiallymoving the puppet in opposition to spring 40 retracting poppet head 21away from valve seat 48. This opens passageway 16 therebyinterconnecting port 13 and port 14.

At the same time if lever 52 is in the position of FIG. 1, where it doesnot engage or react against the end of hexagonal head 22, the cam leverwill exert no force on the poppet so that spring 39 will hold poppethead 37 against valve seat 43 closing passageway 15. Seal 50 assuresthat there then will be no connection between ports 13 and 12 or ports14 and 12.

It can be seen, therefore, that actuation of the poppets is effectedindependently, and simply by pivoting the actuating members through anarc. The cam type of movement of the poppet permits close control of thepoppet, but at the same time is trouble free and easy to operate. All ofthe seals in the valve are particularly effective in preventing anyfluid leakage and, of course, are resistant to elevated temperatures.The construction of the valve is such that the parts will not stick orbecome difficult to operate regardless of the type of usage to which thevalve is applied. Repeated high temperature cycles cause no loss ofeffectiveness of this valve.

When the valve of this invention is used in a bag forming operation, forexample, port 12, which is provided with pipe threads, receives fitting58 of conventional vacuum line 60 connecting to a suitable remote vacuumsource which includes an accumulator 61, and a vacuum pump 62. Port 13is provided with straight threads and fitting 63 engages the valve bodywithin this port. Silicone rubber O-ring 64 seals at the head offittings 63, and the body may be recessed as shown to receive thisO-ring. Stainless steel flexible tubing 65 is connected to fitting 63being brazed or welded at numeral 66 to the inner end of this fitting.This type of connection provides a support for the tubing and a moredurable arrangement results. Fitting 63 holds tubing 65 throughout theaxial length of the fitting, thereby forming an outer tubular supportwhich maintains rigidity adjacent the joint 66 at the end of tubing 65.Because of this, the joint lasts much longer than it would if it wereotherwise positioned, such as at the opposite end of the fitting whereno such support would be provided.

Tubing 65 provides a conduit extending to a bag 67 of airtight, flexiblematerial such as polyvinyl alcohol, as may be seen in FIGS. 4 and 5. Thetubing passes through end 68 of the bag where the edges of upper andlower sheets 70 and 71 are sealed by zinc chromate. A part 72, locatedwithin the bag, is a layup of plastic-impregnated cloth or the like overa die, and is to be pressurized and cured within the bag. Preferably aresin filter trap or debris trap 73 is coupled into tubing 65 that issuitable for collecting resin resulting from the flow, therebypreventing it from reaching the valve where it might cure and immobilizethe moving parts of the valve.

With the elements so arranged, the valve is positioned as schematicallyillustrated in FIG. 6 to close port 14 and open port 12 so that vacuumsource 62 evacuates air from within container 67 through line 65 and thevalve. Ambient atmospheric pressure forces the bag tightly around part72. When this is done, wrinkles 74 form in the bag material around thepart, as seen in FIG. 4, and these must be removed before the assemblyis subjected to heat for curing the part. Instead of breaking the sealat end 68 of the bag, port 12 then is closed disconnecting the interiorof the bag from the vacuum source. After this, port 14 is openedmomentarily so as to bleed in a limited quantity of air to the interiorof the bag, reducing the vacuum. The poppet 21 is easily controlled toallow any desired amount of air to enter the bag so that optimumconditions for moving the wrinkles are obtained. As soon as thiscondition exists, poppet 21 is closed to the position of FIG. 7 so thatthe valve maintains the bag interior sealed both from the atmosphere andfrom the vacuum source and the partial vacuum is maintained. Thewrinkles then are removed, following which poppet 20 is opened(repositioning the valve as shown in FIG. 6) to connect the bag with thesource of vacuum and the part becomes pressurized in a smooth,wrinkle-free bag.

By this arrangement, it is possible to remove the wrinkles from the partmuch more quickly than as accomplished by prior practices withoutwasting or contaminating the vacuum source. It is not necessary to breakthe seal along the edge of the bag at any time and a close control ofthe air supply is obtained so that ideal conditions for removal of thewrinkles can be achieved.

It can be seen from the foregoing, therefore, that I have provided animproved valve of serviceable construction, usable at high temperatureswithout danger of sticking. While by no means limited to such purpose,this valve is especially effective in providing an improved means forcontrolling the vacuum applied to a bag for pressure-forming plasticlaminated parts.

While particular embodiments of the present invention have been shownand described, it will be obvious to those skilled in the art thatchanges and modifications may be made without departing from thisinvention in its broader aspects. and. therefore, the aim in theappended claims is to cover all such changes and modifications as fallwithin the true spirit and scope of this invention.

What is claimed is:

l. A device for applying pressure to a workpiece comprismg:

an airtight container of flexible material;

a conduit communicating with the interior of said container;

a valve connected to said conduit;

an additional conduit connected to said valve;

a source of vacuum connected to said additional conduit;

said valve having an inlet from ambient atmosphere; and

independently controlled means in said valve for selectively connectingsaid first mentioned conduit with said last mentioned conduit; and withsaid inlet to said valve,

said valve includes three ports communicating with said conduits andinlets respectively;

poppet means for selectively controlling the fluid flow through saidconduits and said inlet; and

said control means including lever means for moving said poppet means.

2. The invention as defined in claim 1 including valve seat means ineach of said conduits;

silicone rubber sealing members for engaging said valve seat means;

spring means for urging said sealing members against said valve seatmeans; and wherein said lever means moves said poppet means inopposition to said spring means to a location wherein said sealingmembers are remote from said valve seat means.

3. The invention as defined in claim 1 wherein at least two poppet meansare provided for selectively controlling the communication between oneof said ports and either of the other of said ports.

4. The invention as defined in claim 1 wherein said container includesupper and lower sheets having mated peripheral edges sealed by zincchromate.

5. The invention as defined in claim 1 including a filter coupled intosaid first-mentioned conduit disposed between said valve and saidcontainer.

6. The invention as defined in claim 1 wherein said container is hollowso as to receive a die and a workpiece to be formed about the die andwherein said container comprises a pair of deformable flat sheets havingtheir peripheral edges aligned and sealed together.

7. The invention as defined in claim 1 including a debris trap carriedin said first mentioned conduit disposed between said valve and saidcontainer

2. The invention as defined in claim 1 including valve seat means ineach of said conduits; silicone rubber sealing members for engaging saidvalve seat means; spring means for urging said sealing members againstsaid valve seat means; and wherein said lever means moves said poppetmeans in opposition to said spring means to a location wherein saidsealing members are remote from said valve seat means.
 3. The inventionas defined in claim 1 wherein at least two poppet means are provided forselectively controlling the communication between one of said ports andeither of the other of said ports.
 4. The invention as defined in claim1 wherein said container includes upper and lower sheets having matedperipheral edges sealed by zinc chromate.
 5. The invention as defined inclaim 1 including a filter coupled into said first-mentioned conduitdisposed between said valve and said container.
 6. The invention asdefined in claim 1 wherein said container is hollow so as to receive adie and a workpiece to be formed about the die and wherein saidcontainer comprises a pair of deformable flat sheets having theirperipheral edges aligned and sealed together.
 7. The invention asdefined in claim 1 including a debris trap carried in said firstmentioned conduit disposed between said valve and said container.